Methods which have heretofore been used for the generation of hydrogen gas at a cathode include the electrolysis of an aqueous alkali metal salt solution according to diaphragm processes using a porous filter diaphragm such as an asbestos diaphragm or a dense diaphragm such as an ion exchange membrane, and the electrolysis of water.
Recently, from the viewpoint of saving energy, reduction in electrolytic voltage has been desired. As a method of reducing the electrolytic voltage, it has been desired to reduce hydrogen overvoltage of the cathode.